Yes. It’s 28 days, but employers aren’t required to give public holidays off. 25 + bank holidays is fairly common in my experience, which ends up being more than 28 days.

Yes, though some companies (finance normally) give 5+ weeks on top of bank holidays and very very few employers make you take bank holidays.

At least in Germany we have 30 days without including public holidays.

Same here in France, 30 days on top of public holidays, and if you work more than 35 hours/week, you get the difference in a special type of time off that has some limitations

Are pubic holidays guaranteed on top of that? The UK allowance includes pubic holidays but very few employers make you take them.

They just behave like a randomly-placed Sunday. Most normal work in Germany is not allowed on Sunday (exceptions are mostly work that already operates in shifts).

They are not guaranteed if they land on a weekend, you just have a normal weekend where you cannot shop :)